Fentanyl slows down messages between your brain and body. It is a type of synthetic opioid. Synthetic opioids are drugs made to mimic chemicals in the opium poppy.
Fentanyl for medical use comes as patches, tablets, sprays or injections.
Fentanyl sold without a prescription may come as powder or tablets.
Non-medical use of fentanyl is not as common in Ireland as in other countries. But fentanyl can be sold as other drugs without you knowing. This increases the risk of overdose or drug emergencies.
Drug category: opioid
Opioids are drugs that are made:
- from chemicals in the opium poppy (opiates) - such as heroin
- to mimic the effects of opiates (synthetic opioids) - such as fentanyl or nitazenes
Opioids relieve pain but have a high risk of physical dependency or overdose.
Other names for fentanyl
Other names include: Actiq, Durogesic, fetty, fent, fentanil, Sublimaze
Effects of fentanyl
The effects of fentanyl can vary depending on:
- your size, weight and sex
- if you have any health conditions or mental health difficulties
- how you take the drug
- the strength of the drug
- how much you take
- if you take alcohol, medicines or other drugs at the same time
- where you take the drug and how you feel before you take it
- if you have taken the drug before and how often
Doctors may prescribe fentanyl for pain:
- after an operation or serious injury
- from cancer
- if other painkillers do not work
But the information on this page is about non-medical use of fentanyl. To learn more about a medicine prescribed to you, ask your GP or pharmacist. You can also check the leaflet that comes with the medicine.
What we mean by non-medical use of a medicine
Non-medical use is when someone uses a medicine in a way that does not follow medical guidelines.
This can include when someone uses a medicine:
- they bought in the illegal drug market - this can be online or in person
- that was not prescribed to them
- in a different way or quantity than their doctor prescribed
How you may feel or behave
You may feel:
- relaxed, drowsy or detached
- confused
- intense wellbeing or happiness (euphoria)
Effects on your brain and body
Fentanyl can cause:
- nausea (feeling sick)
- vomiting (getting sick)
- constipation or diarrhoea
- tummy problems such as cramps or increased farting
- problems with thinking or memory
- problems sleeping
- dizziness and coordination problems
- lower blood pressure and heart rate
- problems speaking
- slower breathing
- erection problems
- irregular periods - if you take fentanyl for a long time
- high sensitivity to pain (hyperalgesia) - if you take fentanyl for a long time
- overdose and death - the risk is highest in people with no tolerance to opioids
Fentanyl and mental health
Regular use of fentanyl can cause mental health difficulties or make existing difficulties worse. For example, depression or thoughts of suicide.
If you are dependent on fentanyl or other opioids, it can cause ongoing stress.
If you use opioids and have mental health difficulties, you can get support for both.
Fentanyl and dependency
Regular use of fentanyl can cause:
- tolerance - when you need to take more of the drug to get the same effects
- dependency
Signs of dependency can include:
- cravings for a drug
- withdrawal symptoms
- continuing to use a drug even when it causes you harm
Withdrawal symptoms
Withdrawal symptoms from fentanyl can include:
- nausea or vomiting
- muscle aches
- diarrhoea
- sweating and chills
- sneezing
- yawning
- sleep problems
- mood swings
It is not safe to suddenly stop taking opioids without medical advice.
If you want to stop taking fentanyl, you can get support from:
- your GP or practice nurse
- a drug and alcohol service
How long does fentanyl stay in your system?
It can be hard to know how long fentanyl stays in your system.
There are tests to detect fentanyl. But different types of tests have different detection times.
Things that affect how long a drug stays in your system
The time it takes for a drug to leave your system depends on many things.
For example:
- how much you took
- how often you take the drug
- how strong the drug was
- your age, sex and metabolism
- your general health
Reducing risks from opioids
It’s always safest not to take drugs or medicines that are not prescribed to you. The strength and contents of drugs can vary. Your dealer does not always know the contents of what they sell.
Fentanyl sold without a prescription is usually different from fentanyl for medical use.
For example, it can be:
- stronger or another type of fentanyl
- another synthetic opioid
- sold as another drug, such as oxycodone
This increases the risk of overdose.
Most people do not choose to use fentanyl.
There are ways to reduce the risk of harm if you use fentanyl or other opioids. Select a piece of advice to find out more.
Be with people you trust and look out for each other - do not use alone.
Pick a meeting point and know what to do in case of an emergency.
Use a buddy system if possible.
Prepare a plan with your buddy on what to do in case of an emergency.
This may be that you both agree to:
- learn the signs of an overdose
- use naloxone in an opioid emergency
- call the emergency services
- stay with the other person until help arrives
Start with a small amount and wait 2 hours before you take more.
This is to reduce the risk of an overdose or drug emergency.
The contents or strength of drugs can vary, even in the same batch.
If you start with a small amount, you can:
- see how you react
- stop if you get an effect you did not expect or do not want
It can take up to 2 hours for some effects to happen. If you take too much too soon, it increases your risk.
Only use 1 substance at a time.
Using opioids with alcohol, medicines or other drugs can have unpredictable and negative effects. Mixing drugs is always more risky.
Get and carry naloxone.
Naloxone is a prescription medicine that can temporarily reverse the effects of opioids. It can help prevent death from an overdose.
If you are at risk of an opioid overdose, you can get a naloxone kit through your GP or other services.
Give a naloxone kit to another person - this could be a family member, friend or someone who is around you when you use.
Know what to do in case of a drug emergency.
If you take any kind of drug, it is important to know:
- signs of a drug emergency, including signs related to mental health
- what to do in case of overdose or other emergencies
An overdose can be a life-threatening condition. It happens when someone has too much of a drug or another substance in their system.
Getting help can prevent serious damage or death. Your wellbeing is the main priority.
Check our drug alerts for extra risky drugs in Ireland.
We issue alerts if extra risky drugs are found in Ireland.
Follow us for updates on drug monitoring:
Mixing fentanyl with alcohol or other drugs
Using fentanyl with alcohol, medicines or other drugs can have unpredictable and negative effects.
The risk of overdose or negative effects is higher if you mix fentanyl with substances that slow down messages between the brain and the body.
For example:
- alcohol
- benzos
- G (GHB or GBL)
Emergency action required: Call 112 or 999 if
you or someone else has taken a drug and has:
- severe drowsiness or problems staying awake
- pinpoint pupils
- hallucinations
- a seizure (fit)
- lost consciousness
- slow breathing or other problems breathing - they may make a snoring or gurgling sound
- cold and clammy skin - white skin may turn blue, black or brown skin may turn grey
- chest pain
Use naloxone if you have it.
Tell the medics everything you know about the drug and give them any leftover drug if possible. It will help them decide the right treatment.
If you are worried about fentanyl use
If you are worried about your own or someone else’s use, you can get support. This can be when fentanyl use affects your health, relationships, work or other areas of your life.
Non-urgent advice: Drugs and alcohol helpline
You can contact the helpline for support, information or advice on treatment and support options.
Freephone: 1800 459 459
Monday to Friday, 9.30am to 5.30pm
Email: helpline@hse.ie